1,2,4-Benzothiadiazine-1-oxides are known in the art. For example, U.S. Pat. No. 3,936,977 discloses 1-phenyl (or substituted phenyl)-1H-1,2,4-benzothiadiazine-3(4H)-ones bearing a substituent on the C-3 nitrogen and permissible substituents in the phenyl ring of the benzothiadiazine including alkoxy. The compounds disclosed therein are stated to be central nervous system depressants and diuretics. U.S. Pat. No. 3,957,769 discloses 1-phenyl (or substituted phenyl) 3-amino (or alkylamino or dialkylamino)-1H-1,2,4-benzothiadiazine-1-oxides which may permissibly be substituted in the phenyl ring of the benzothiadiazine with, among other groups, an alkoxy group. These compounds are also said to be central nervous system depressants and diuretics. Specifically disclosed are 7-methoxy-3-methyl-amino-1-phenyl-1,2,4-benzothiadiazine-1-oxide and 6-methoxy-3-methylamino-1-phenyl-7-sulfamyl-1,2,4-benzothiadiazine-1-oxide . U.S. Pat. No. 3,933,805 disclosed 1-phenyl (or substituted phenyl) 3-dialkylaminomethyl-1H-1,2,4-benzothiadiazine-1-oxides permissibly substituted with methoxy in the phenyl ring of the benzothiadiazine molecule. The compounds are said to be anti-hypertensives. Stoss and Satzinger, Chem. Ber., 109, 2097 (1976) prepared 1-phenyl or 1-methyl-3-amino-1H-1,2,4-benzothiadiazine-1-oxides containing a methyl or chloro substituent in the benzene ring portion of the benzothiadiazine ring. An imino group substituted at the 3 position of the benzothiadiazine ring is illustrated in Tables 1 and 2 of the article. Cohnen and Mahnke, Chem. Ber., 105, 757, (1972) described on page 758, compound 7jA which is 1-phenyl-3-methylaminomethyl-7-chloro-1H-1,2,4-benzothiadiazine-1-oxide. The compounds described therein were employed as intermediates for the preparation of Librium-like drugs.
1-Substituted-6,7-dialkoxy-(methoxy, ethoxy, or methylene dioxy)-1H-1,2,4-benzothiadiazine-1-oxides carrying a direct attached amino group in the 3-position have not been disclosed, either generically or specifically, in the prior art.